Subscribers of telecommunications services receive those services from telecommunications providers via co-axial cable, twisted pair of copper wiring, optical fiber and other transmission or communications lines. The communications lines are brought to the subscriber (customer) premises and connected to wiring and components within the premises at an enclosure known as a network interface device (NID). The NID often serves as a demarcation point between the service provider network and the wiring at the subscriber premises, delineating the customer's responsibility (repair and maintenance of all wiring and other facilities on the subscriber side of the interface) and the service provider's responsibility (repair and maintenance of all wiring and other facilities on the network side of the interface).
As services have become more complex (beyond the provision of simple telephone services), the complexity of the NID has also increased. For example, the provision of high speed data service, such as digital subscriber line (DSL) service, over a traditional telephone (twisted pair) line requires the use of a DSL modem and sometimes other active electronic components (depending on the level of service). While those active components can be located within the customer premises, it is often desirable to locate them within the NID at the exterior of the customer premises. The exterior may be a convenient location for the service provider, e.g., when access is needed to add components and wiring in order to change or enhance service, and to maintain wiring and facilities without having to enter the subscriber premises.
When active components in a NID are located at the exterior of the subscriber premises, it becomes necessary to consider the operating conditions of the components, particularly dissipating heat generated during operation (as described herein, the term “active components” means electronic components that generate heat, usually because they are powered by electrical power—however, the present invention is not necessarily so limited). Under some circumstances, it may become necessary to provide active cooling (fans or other devices), which themselves require electrical power. While it is possible to power the active cooling devices from the subscriber premises (e.g., via connection to the customer's household power) or from the network over a network power line (e.g., separate from the communications line), such arrangements are costly to implement.